Cookbook:Ketchup

Ketchup, also known as catsup, is a type of sauce containing spices and a large amount of acid (vinegar or lactic acid), typically tomato-based. Some recipes, particularly those from Australia, may use the ambiguous term tomato sauce to mean tomato ketchup.

Interestingly, the original ketchup did not include tomatoes. It was probably a Chinese sauce called "ke-tsiap", based on fermentedbrined fish or shellfish. The sauce was brought back to Europe by sailors, and appropriated into local recipes. Later, tomatoes were added.